body {        /*背景*/
    background-image: url('../images/4.jpg');
    background-size:cover;/*裁切页面*/
    padding: 0;
    margin: 0;
}
ul{
    list-style-type: none; /*清除无序列表前的小点*/
    width: auto;
    height: 60px;
    background: rgb(0,135,181);
    margin: 0;
    padding-left: 14%;/*左边距，使li看起来在中间*/
    /*position: relative;*/
    text-align: center;
}
li a{
    float: left;
    width: 180px;
    height: 60px;
    padding: 0px;
    margin-right: 2%;  /*两个li之间的距离*/
    font-size: 30px;
    background-image:linear-gradient(to left,rgb(0,135,181),rgb(0,190,255));
    color: #FFFFFF;
    text-align: center;
    text-decoration: none; /*去下划线*/
}
form{
    width: 600px;
    height: 400px;
    /*border: 3px solid #3399cc;*/
    background-color: rgb(255,255,255,0.3);
    margin-left: auto;
    margin-right: auto;
    margin-top: 70px;
    padding-left:30%;
    padding-top: 130px;
    animation: popIn 1.9s;
    border-radius: 50px;
}
form a{
    font-size: 100px;
}
#update{
    font-size: 40px;
    color: rgb(0,135,181);
}
@keyframes popIn {
    0% {
        opacity: 0;
    }
    100% {
        opacity: 1;
    }
}

label{
    font-size: 30px;
}
#f{
    background-color: rgb(255,255,255,0.6);
    width: 250px;
    text-align: center;
    border-radius: 20px;
}
input{
    height: 40px;
    border-radius: 5px;
    text-align: center;
}
button{
    height: 40px;
    width: 90px;
    margin-top: 4px;
    margin-left: 140px;
    border-radius: 5px;

}